

While you can probably use them for some small tasks (like a switch, a file server with a USB thumb drive or a print server), you’re probably better off if you can sell them and buy a raspberry pi or similar.
The Fritzbox 7530 for example could be sold for 50€ (at least in my country).
Probably overkill, but for projects like this I’ve setup WordPress in the past. Once everything was done, I converted the WordPress page to a static site with httrack and use the static version.
This gives the ease of setting up and editing combined with the stability and security of a static HTML website.